Question

prove by mathematical induction n2+n is even

Answer 1

n2+n,
n is even no.,-2,0,2,4,6,8........

n=-2, -2(2)+-2=-2,
n=0, 0(2)+0=0
n=2, 2(2)+2=6
n=4, 4(2)+4=12

-2,0,6,12,18......